/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2008, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id: hostip4.c,v 1.47 2008-11-06 17:19:57 yangtse Exp $
 ***************************************************************************/

#include "setup.h"


#ifdef NEED_MALLOC_H
#include <malloc.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>     /* required for free() prototypes */
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>     /* for the close() proto */
#endif
#ifdef  VMS
#include <in.h>
#include <inet.h>
#include <stdlib.h>
#endif

#ifdef HAVE_PROCESS_H
#include <process.h>
#endif

#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "strerror.h"
#include "url.h"
#include "inet_pton.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <api/libcurl/mprintf.h>

#include "memory.h"
/* The last #include file should be: */
#include "memdebug.h"

/***********************************************************************
 * Only for plain-ipv4 builds
 **********************************************************************/
#ifdef CURLRES_IPV4 /* plain ipv4 code coming up */
/*
 * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
 * been set and returns TRUE if they are OK.
 */
bool Curl_ipvalid(struct SessionHandle *data)
{
	if (data->set.ip_version == CURL_IPRESOLVE_V6)
		/* an ipv6 address was requested and we can't get/use one */
		return FALSE;

	return TRUE; /* OK, proceed */
}

#ifdef CURLRES_SYNCH /* the functions below are for synchronous resolves */

/*
 * Curl_getaddrinfo() - the ipv4 synchronous version.
 *
 * The original code to this function was from the Dancer source code, written
 * by Bjorn Reese, it has since been patched and modified considerably.
 *
 * gethostbyname_r() is the thread-safe version of the gethostbyname()
 * function. When we build for plain IPv4, we attempt to use this
 * function. There are _three_ different gethostbyname_r() versions, and we
 * detect which one this platform supports in the configure script and set up
 * the HAVE_GETHOSTBYNAME_R_3, HAVE_GETHOSTBYNAME_R_5 or
 * HAVE_GETHOSTBYNAME_R_6 defines accordingly. Note that HAVE_GETADDRBYNAME
 * has the corresponding rules. This is primarily on *nix. Note that some unix
 * flavours have thread-safe versions of the plain gethostbyname() etc.
 *
 */
Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
								const char *hostname,
								int port,
								int *waitp)
{
#if defined(HAVE_GETHOSTBYNAME_R_3)
	int res;
#endif
	Curl_addrinfo *ai = NULL;
	struct hostent *h = NULL;
	struct in_addr in;
	struct hostent *buf = NULL;

#ifdef CURL_DISABLE_VERBOSE_STRINGS
	(void)conn;
#endif

	*waitp = 0; /* don't wait, we act synchronously */

	if (Curl_inet_pton(AF_INET, hostname, &in) > 0)
		/* This is a dotted IP address 123.123.123.123-style */
		return Curl_ip2addr(AF_INET, &in, hostname, port);

#if defined(HAVE_GETHOSTBYNAME_R)
	/*
	 * gethostbyname_r() is the preferred resolve function for many platforms.
	 * Since there are three different versions of it, the following code is
	 * somewhat #ifdef-ridden.
	 */
	else
	{
		int h_errnop;

		buf = calloc(CURL_HOSTENT_SIZE, 1);
		if (!buf)
			return NULL; /* major failure */
		/*
		 * The clearing of the buffer is a workaround for a gethostbyname_r bug in
		 * qnx nto and it is also _required_ for some of these functions on some
		 * platforms.
		 */

#ifdef HAVE_GETHOSTBYNAME_R_5
		/* Solaris, IRIX and more */
		h = gethostbyname_r(hostname,
							(struct hostent *)buf,
							(char *)buf + sizeof(struct hostent),
							CURL_HOSTENT_SIZE - sizeof(struct hostent),
							&h_errnop);

		/* If the buffer is too small, it returns NULL and sets errno to
		 * ERANGE. The errno is thread safe if this is compiled with
		 * -D_REENTRANT as then the 'errno' variable is a macro defined to get
		 * used properly for threads.
		 */

		if (h)
		{
			;
		}
		else
#endif /* HAVE_GETHOSTBYNAME_R_5 */
#ifdef HAVE_GETHOSTBYNAME_R_6
			/* Linux */

			(void)gethostbyname_r(hostname,
								  (struct hostent *)buf,
								  (char *)buf + sizeof(struct hostent),
								  CURL_HOSTENT_SIZE - sizeof(struct hostent),
								  &h, /* DIFFERENCE */
								  &h_errnop);
		/* Redhat 8, using glibc 2.2.93 changed the behavior. Now all of a
		 * sudden this function returns EAGAIN if the given buffer size is too
		 * small. Previous versions are known to return ERANGE for the same
		 * problem.
		 *
		 * This wouldn't be such a big problem if older versions wouldn't
		 * sometimes return EAGAIN on a common failure case. Alas, we can't
		 * assume that EAGAIN *or* ERANGE means ERANGE for any given version of
		 * glibc.
		 *
		 * For now, we do that and thus we may call the function repeatedly and
		 * fail for older glibc versions that return EAGAIN, until we run out of
		 * buffer size (step_size grows beyond CURL_HOSTENT_SIZE).
		 *
		 * If anyone has a better fix, please tell us!
		 *
		 * -------------------------------------------------------------------
		 *
		 * On October 23rd 2003, Dan C dug up more details on the mysteries of
		 * gethostbyname_r() in glibc:
		 *
		 * In glibc 2.2.5 the interface is different (this has also been
		 * discovered in glibc 2.1.1-6 as shipped by Redhat 6). What I can't
		 * explain, is that tests performed on glibc 2.2.4-34 and 2.2.4-32
		 * (shipped/upgraded by Redhat 7.2) don't show this behavior!
		 *
		 * In this "buggy" version, the return code is -1 on error and 'errno'
		 * is set to the ERANGE or EAGAIN code. Note that 'errno' is not a
		 * thread-safe variable.
		 */

		if (!h) /* failure */
#endif/* HAVE_GETHOSTBYNAME_R_6 */
#ifdef HAVE_GETHOSTBYNAME_R_3
			/* AIX, Digital Unix/Tru64, HPUX 10, more? */

			/* For AIX 4.3 or later, we don't use gethostbyname_r() at all, because of
			 * the plain fact that it does not return unique full buffers on each
			 * call, but instead several of the pointers in the hostent structs will
			 * point to the same actual data! This have the unfortunate down-side that
			 * our caching system breaks down horribly. Luckily for us though, AIX 4.3
			 * and more recent versions have a "completely thread-safe"[*] libc where
			 * all the data is stored in thread-specific memory areas making calls to
			 * the plain old gethostbyname() work fine even for multi-threaded
			 * programs.
			 *
			 * This AIX 4.3 or later detection is all made in the configure script.
			 *
			 * Troels Walsted Hansen helped us work this out on March 3rd, 2003.
			 *
			 * [*] = much later we've found out that it isn't at all "completely
			 * thread-safe", but at least the gethostbyname() function is.
			 */

			if (CURL_HOSTENT_SIZE >=
					(sizeof(struct hostent) + sizeof(struct hostent_data)))
			{

				/* August 22nd, 2000: Albert Chin-A-Young brought an updated version
				 * that should work! September 20: Richard Prescott worked on the buffer
				 * size dilemma.
				 */

				res = gethostbyname_r(hostname,
									  (struct hostent *)buf,
									  (struct hostent_data *)((char *)buf +
															  sizeof(struct hostent)));
				h_errnop = SOCKERRNO; /* we don't deal with this, but set it anyway */
			}
			else
				res = -1; /* failure, too smallish buffer size */

		if (!res)  /* success */
		{

			h = buf; /* result expected in h */

			/* This is the worst kind of the different gethostbyname_r() interfaces.
			 * Since we don't know how big buffer this particular lookup required,
			 * we can't realloc down the huge alloc without doing closer analysis of
			 * the returned data. Thus, we always use CURL_HOSTENT_SIZE for every
			 * name lookup. Fixing this would require an extra malloc() and then
			 * calling Curl_addrinfo_copy() that subsequent realloc()s down the new
			 * memory area to the actually used amount.
			 */
		}
		else
#endif /* HAVE_GETHOSTBYNAME_R_3 */
		{
			infof(conn->data, "gethostbyname_r(2) failed for %s\n", hostname);
			h = NULL; /* set return code to NULL */
			free(buf);
		}
#else /* HAVE_GETHOSTBYNAME_R */
	/*
	 * Here is code for platforms that don't have gethostbyname_r() or for
	 * which the gethostbyname() is the preferred() function.
	 */
	else
	{
#if (defined(NETWARE) && !defined(__NOVELL_LIBC__))
		h = gethostbyname((char*)hostname);
#else
		h = gethostbyname(hostname);
#endif
		if (!h)
			infof(conn->data, "gethostbyname(2) failed for %s\n", hostname);
#endif /*HAVE_GETHOSTBYNAME_R */
	}

	if (h)
	{
		ai = Curl_he2ai(h, port);

		if (buf) /* used a *_r() function */
			free(buf);
	}

	return ai;
}

#endif /* CURLRES_SYNCH */
#endif /* CURLRES_IPV4 */

